Author
 |
Berdahl, John |
|
Ries, Ronald |
|
Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/23/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Russian wildrye, an introduced, cool-season bunchgrass, provides valuable pasture with high forage quality. Russian wildrye pastures have been seeded on approximately 750,000 acres in semiarid regions of the U.S.A. to complement native rangeland, but poor seedling vigor limits more widespread use of this grass. Previous greenhouse studies indicated that doubling the echromosome number of normal diploid Russian wildrye resulted in tetraploid plants with larger cell size and improved seedling vigor. We found that initial seedling emergence of diploids averaged about two-thirds that of tetraploids in both early and late field plantings. Furthermore, tetraploid seedlings were able to emerge from greater planting depths than diploids in a controlled environment. Tetraploid seedlings had larger leaf size than diploids, but no differences were found in leaf number. We concluded that seedling vigor of tetraploid Russian wildrye can be improved dbeyond the limits that are possible from continued selection and breeding of diploid plants. Improved seedling vigor should increase the use of Russian wildrye for complementary pasture and for establishment of permanent vegetative cover on highly erosive croplands. This would result in a more stable base of high quality pasture in semiarid regions. Technical Abstract: Poor seedling vigor limits the use of Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski] for complementary pasture. Tetraploid (2n=4x=28) plants of Russian wildrye have had high seedling vigor in greenhouse studies compared to diploid (2n=2x=14) plants. Objectives of this research were (i) to compare seedling emergence and development of diploid and tetraploid Russian wildrye in solid-seeded, single-row field plots and (ii to document early seedling development and morphology in a controlled environment chamber. Seed mass averaged 2.70 and 4.66 mg per seed, respectively, for diploids and tetraploids. Initial seedling emergence averaged approximately 33% higher for tetraploids than diploids in field tests. Tiller number averaged only slightly higher for diploids than tetraploids in solid-seeded rows. Larger leaf size did not result in fewer leaves for tetraploids. Seedling emergence from a 63-mm depth averaged 46% %for tetraploids and 10% for diploids at a 16/13C diurnal temperature regim and 11 and 6%, respectively, for tetraploids and diploids at a 23/18C temperature regime. Coleoptile length increased from 42 to 61 mm for tetraploids and from 43 to 49 mm for diploids when temperatures were reduced. Tetraploid Russian wildrye provides a unique germplasm pool from which additional improvement in seedling vigor can be accomplished beyond the limits that are possible from continued selection in diploid germplasm. |
